Monday, September 16, 2013

For thousands of years, humans have looked to the stars for guidance on their long journeys. But humans aren't alone in their reliance on the heavens.

Research released earlier this year suggested that dung beetles also look to the night sky for navigation — albeit not quite in the same way we do. Last week, the authors of the dung beetle research earned an Ig Nobel (an award with the tagline "For achievements that first make people laugh then make them think).

Also last week, astronomer Michael J. West from the Maria Mitchell Observatory published an article on the arxiv raising the idea that whales use the stars to navigate across vast migratory distances. Although the article errs on the side of speculation (it's not intended to be a peer-reviewed research article), West's piece raises some interesting questions about how some mammals adapt to both their immediate and celestial surroundings.

One astronomer speculates that humpback whales may use the stars to guide them during migrations.
Image Credit: Tim Vo

For the dung beetle research, an international team of scientists found a controlled environment when they could turn the stars off with a flick of a switch — a planetarium. The research team observed the beetles' movements under a completely dark sky and one lit by the milky way. Under the dark sky, the beetles roamed aimlessly and haphazardly, but under the star-lit sky, the beetles moved their dung in more direct, straight paths.

Creating a similar experiment for whales is certainly unfeasible, at least at any planetarium here on Earth. Nonetheless, several observations of humpback whales' migrations seem to defy most explanations. For instance, humpbacks will travel for thousands of miles across the ocean with no Earthly landmarks, and they travel in an almost perfectly straight line. Despite a variety of obstacles that could steer them off course (West mentions currents, storms, and varying sea floor depths in his article), their direction stays true.

Prior research has shown that whales use the Earth's magnetic field to orient themselves, and they may also use the sun to keep them oriented during the day. Nonetheless, researchers behind an extensive study of Humpback whale migrations two years ago doubt that these two factors can solely explain the humpbacks' precision. Perhaps the stars also play a role.

Although whales spend most of their time underwater, they have been seen peeking above the water for minutes at a time, a behavior known as spyhopping. Although their vision may not be as good as humans, it's possible that glimpses toward the night sky could guide the whales according to West.

The connection between the stars and whales' precise migratory paths remains far from proven, however, as West readily admits in his paper. Also, other animals that do use the night sky for navigation don't rely on it the same way humans do. The dung beetles, for instance, use the Milky Way as a visual cue, but they don't use specific stars to point them in a particular direction, such as north.

Whales may use stars in a similar fashion to the dung beetles: as a reference point to keep them on track. Scientists probably won't know for sure until they dump some whales in an enormous water-filled planetarium, however. Sometimes, science is best left with its mystery intact.